Hypothesis for retroviral causation of rheumatoid arthritis.

Over the past year, convincing direct evidence that rheumatoid arthritis is caused by a retrovirus has not been presented. Strong support for this hypothesis, however, comes from an impressive body of recent work demonstrating that human T-cell lymphotropic virus type I causes a destructive arthropathy that has many of the same features as rheumatoid arthritis. Additional strong support for the hypothesis is provided by the resemblance of the arthropathies induced by caprine arthritis encephalitis and the ovine maedi-visna viruses to rheumatoid arthritis. These retroviral infections emphasize the potential complexity of detecting retroviral involvement and proving its importance in the causation of rheumatoid arthritis. Retroviruses clearly possess diverse pathways for involvement in autoimmune diseases.